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This Article Accepted manuscript (PDF) All Versions of this Article: EJE-08-0205v1 159/5/517    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Jimenez, C. Articles by Gagel, R. PubMed PubMed Citation Articles by Jimenez, C. Articles by Gagel, R.

Follow-up of Pituitary Tumor Volume in Patients with Acromegaly Treated with Pegvisomant in Clinical Trials

C Jimenez, Endocrine Neoplasia and Hormonal Disorders, The University of Texas M.D. Anderson Cancer Center, Houston, 77025, United States
P Burman, Department of Endocrinology, University Hospital, Malmö, Sweden
R Abs, Department of Endocrinology, University of Antwerp, Antwerp, Belgium
D Clemmons, Division of Endocrinology, University of North Carolina School of Medicine, Chapel Hill, United States
W Drake, Dept of Endocrinology, St Bartholomews Hospital, London, United Kingdom
K Hutson, Department of Radiology, University of Tennessee College of Medicine, Chattanooga, United States
M Messig, Clinical R&D Statistics, New York, United States
M Thorner, Department of Medicine, Endocrinology and Metabolism, University of Virginia, Charlottesville, United States
P Trainer, Department of Endocrinology, Christie Hospital, Manchester, United Kingdom
R Gagel, Section of Endocrinology, MD Anderson Cancer Center, Houston, United States

Correspondence: Camilo Jimenez, Email: cjimenez{at}mdanderson.org

Abstract

Objective: We examined pituitary tumor volumes in patients treated with pegvisomant for 18 months or longer, and in whom the tumors were monitored for at least 3 years. We present details on nine of 304 patients in clinical trials with pegvisomant who experienced tumor growth within the first year of treatment.

Method: MRI images prior to start of pegvisomant and at last follow-up were examined in forty-three patients (14% of participating patients). Twenty-nine had received prior radiation therapy (18% of irradiated patients) and all but five received somatostatin analogues between periods of pegvisomant treatment.

Results: At follow-up, the median tumor volume was 0.6 cc (range 0.0-19.7 cc), in comparison with 1.6 cc (0.0-19.7 cc) at baseline (p <0.001). Twenty-five patients, of who 23 received radiation therapy, had tumor volume reduction. Seventeen patients had no significant change. One patient, who had not received radiation therapy, had an increase in tumor volume from 1.61 cc to 1.93 cc. Of the nine patients with tumor growth, six had progressive growth before initiating pegvisomant. Two patients with stable tumors while on octreotide experienced enlargement after octreotide discontinuation but remained stable on long-term pegvisomant therapy.

Conclusion: The present data indicate that pegvisomant does not promote tumor growth and suggest that the nine observed cases of tumor progression, which occurred within eight months after commencing pegvisomant, are likely rebound expansions after discontinuation of somatostatin analogues and/or the natural history of aggressively growing pituitary tumors. Continued long-term surveillance of tumor volume, particularly in non-irradiated patients, is recommended.